HTTP Tunnel - can pass though firewall !!

Yesterday, night I was checking for a IRC person's logon connection detail, then this bring me to read about the shell account (SSH access to remote server, for testing OS or running IRC client/bots, testing scripts..etc)... then further reading it, I found some information about how to access to remote external servers, if we are behind a NAT router or firewall -- by using HTTP-Tunnel technology which it allows users to do internet tasks despite the restrictions imposed by firewalls. This is made possible by sending data through HTTP (port 80). Hmmm... I still need to read more on this...